Change the speed of audio

Which speed for what

Speech copes well with being sped up, since much of it is pauses and drawn-out vowels. Many people follow 1.5× easily after a few minutes, and 2× works for skimming. For music practice, 0.75× is often slow enough to catch every note while it still sounds like music. Octoolo does not turn speech into text, so the slow speeds are there for typing it out yourself.

Speed without the chipmunk effect

Play a tape or a record faster and the voices go up in pitch, because every sound wave is squeezed. Octoolo uses time stretching instead (FFmpeg's atempo filter): it changes how long the sound lasts while each note and each voice stays at its own pitch. The editor says so right under the speed chips: the pitch stays the same.

Stretching has limits of its own. Speech stays clear across the whole range. Music slowed to 0.5× can sound slightly smeared, with drums and plucked strings losing some of their snap, because every moment has to be drawn out to twice its length. If that bothers you, 0.75× is gentler.

What Octoolo cannot do is the opposite: change the pitch and keep the speed. There is no setting to move a song into another key or to make a voice deeper or higher.

Different speeds in one recording

Speed belongs to each sound on the track, not to the whole project. Split a long recording with S and you can speed up the slow middle of a talk while the questions at the end stay at 1×, or slow down only the tricky bars of a song. Fades and Volume still work on every piece.

One thing to know: a faster sound gets shorter, and the sounds after it stay where they were. That leaves a gap of silence behind it. Drag the following sounds to the left until they snap against it, and the recording flows on again. Slowing a sound down does the opposite and can make it run over the next one, so play the joins before you export.

Once it sounds right, a short fade at each new edge keeps the changes of speed from feeling abrupt.

Shorter recordings without rushing them

Speed is not the only way to save listening time, and it works better combined with a little cutting. Recorded talks and meetings tend to carry a lot of dead air: the minutes before everyone arrives, a break in the middle, long silences while someone looks for a slide.

• Trim the start and the end down to where the talking begins and stops.
• Split around long pauses and breaks, delete them, and slide the rest together.
• Then pick a modest speed, such as 1.25×, for what is left.

A recording cut this way often ends up much shorter while still sounding like natural speech, which is easier on listeners than 2× on its own. The Export dialog shows the final length before you save, so you can check the time you have saved.